Exhibit 12

Potash Corporation of Saskatchewan Inc.

Ratio of Earnings to Fixed Charges

(in millions of US dollars, except ratio amounts)

(unaudited)



|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|------------------------------------------------------- |  | ---------------------- | ----- | - | ---- | - | ----- | ---- |  | - | ------- | - |  | ------- | ----- | - |  | - | ----- | -
|                                                        |  | Year ended December 31 |      
|                                                        |  | 2012                   |       |   | 2011 |   |       | 2010 |  |   | 2009(1) |   |  | 2008(1) |      
|Net income                                              |  | $                      | 2,079 |   |      | $ | 3,081 |      |  | $ | 1,775   |   |  | $       | 981   |   |  | $ | 3,466 |  
|Income taxes                                            |  |                        | 826   |   |      |   | 1,066 |      |  |   | 701     |   |  |         | 79    |   |  |   | 1,060 |  
|Share of earnings of equity investees                   |  |                        | (278  | ) |      |   | (261  | )    |  |   | (174    | ) |  |         | (134  | ) |  |   | (256  | )
|Fixed charges                                           |  |                        | 272   |   |      |   | 300   |      |  |   | 285     |   |  |         | 256   |   |  |   | 187   |  
|Amortization of capitalized interest                    |  |                        | 18    |   |      |   | 14    |      |  |   | 8       |   |  |         |      |   |  |   |      |  
|Distributed income of equity investees                  |  |                        | 211   |   |      |   | 128   |      |  |   | 79      |   |  |         | 131   |   |  |   | 89    |  
|Interest capitalized                                    |  |                        | (102  | ) |      |   | (84   | )    |  |   | (107    | ) |  |         | (68   | ) |  |   | (43   | )
|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|Total Earnings Available for Fixed Charges              |  | $                      | 3,026 |   |      | $ | 4,244 |      |  | $ | 2,567   |   |  | $       | 1,245 |   |  | $ | 4,503 |  
|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|                                                        |  |                        |       |   |     
|Fixed Charges                                           |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|                                                        |  |                        |       |   |     
|Interest expensed and capitalized                       |  | $                      | 244   |   |      | $ | 273   |      |  | $ | 259     |   |  | $       | 227   |   |  | $ | 161   |  
|Amortization of debt issue costs                        |  |                        | 5     |   |      |   | 5     |      |  |   | 5       |   |  |         | 3     |   |  |   | 2     |  
|Estimated portion of rent expense representing interest |  |                        | 23    |   |      |   | 22    |      |  |   | 21      |   |  |         | 26    |   |  |   | 24    |  
|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|Total Fixed Charges                                     |  | $                      | 272   |   |      | $ | 300   |      |  | $ | 285     |   |  | $       | 256   |   |  | $ | 187   |  
|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  
|                                                        |  |                        |       |   |     
|Ratio of Earnings to Fixed Charges                      |  |                        | 11.13 |   |      |   | 14.15 |      |  |   | 9.01    |   |  |         | 4.86  |   |  |   | 24.08 |  
|                                                        |  |                        |       |   |      |   |       |      |  |   |         |   |  |         |       |   |  |   |       |  



|(1) | As the company adopted IFRS with effect from January 1, 2010, our 2008 and 2009 information is presented on a previous Canadian GAAP basis. Accordingly,
information for prior years may not be comparable to 2010, 2011 and 2012.
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